TOYOTA PRIUS PRIME 2021 Owners Manual (in English)

PRIUS PRIME_OM_OM47D71U_(U)
4015-5. Using the driving support systems
5
Driving
■Steering assist function
When the system determines
that the vehicle might depart
from its lane or course
*, the
system provides assistance as
necessary by operating the
steering wheel in small
amounts for a short period of
time to keep the vehicle in its
lane.
If the system detects that the
steering wheel has not been
operated for a fixed amount of
time or the steering wheel is not
being firmly gripped, a warning
is displayed on the multi-infor-
mation display and the function
is temporarily canceled.
*: Boundary between asphalt and the side of the road, such as grass, soil, or
a curb
■
Vehicle sway warning function
When the vehicle is swaying
within a lane, the warning
buzzer will sound and a mes-
sage will be displayed on the
multi-information display to alert
the driver.

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PRIUS PRIME_OM_OM47D71U_(U)
5-5. Using the driving support systems
■Lane centering function
This function is linked with
dynamic radar cruise control
with full-speed range and pro-
vides the required assistance
by operating the steering wheel
to keep the vehicle in its current
lane.
When dynamic radar cruise con-
trol with full-speed range is not
operating, the lane centering
function does not operate.
In situations where the white
(yellow) lane lines are difficult to
see or are not visible, such as
when in a traffic jam, this func-
tion will operate to help follow a
preceding vehicle by monitoring
the position of the preceding
vehicle.
If the system detects that the steering wheel has not been operated for
a fixed amount of time or the steering wheel is not being firmly gripped,
a warning is displayed on the multi-information display and the function
is temporarily canceled.

PRIUS PRIME_OM_OM47D71U_(U)
4035-5. Using the driving support systems
5
Driving
Press the LTA switch to turn the
LTA system on.
The LTA indicator illuminates and a
message is displayed on the multi-
information display.
Press the LTA switch again to turn
the LTA system off.
When the LTA system is turned on
or off, operation of the LTA system
continues in the same condition
the next time the hybrid system is
started.
Tu r n i n g LTA s y s t e m o n

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PRIUS PRIME_OM_OM47D71U_(U)
5-5. Using the driving support systems
LTA i n d i c a t o r
The illumination condition of the
indicator informs the driver of
the system operation status.
Illuminated in green: LTA sys-
tem is operating.
Flashing in orange: Lane
departure alert function is oper-
ating.
Steering control indicator and operation display of steering wheel
operation support
When that steering wheel assistance of the steering assist function
or lane centering function is operating, the indicator illuminates and
the operation display on the multi-information display is turned on.
Lane departure alert function display
Displayed when the multi-information display is switched to the
driving assist system information screen.
*: Boundary between asphalt and the side of the road, such as grass, soil, or
a curb
Indications on combination meter
1
2
3
Inside of displayed lines is
whiteInside of displayed lines is
black
Indicates that the system is recog-
nizing white (yellow) lines or a
course
*. When the vehicle
departs from its lane, the white
line displayed on the side the
vehicle departs from flashes
orange.Indicates that the system is not
able to recognize white (yellow)
lines or a course* or is temporar-
ily canceled.

PRIUS PRIME_OM_OM47D71U_(U)
4055-5. Using the driving support systems
5
Driving
Follow-up cruising display
Displayed when the multi-information display is switched to the driving
assist system information screen.
Indicates that steering assist of the lane centering function is operating by
monitoring the position of a preceding vehicle.
When the follow-up cruising display is displayed, if the preceding vehicle
moves, your vehicle may move in the same way. Always pay careful atten-
tion to your surroundings and operate the steering wheel as necessary to
correct the path of the vehicle and ensure safety.
■Operation conditions of each function
●Lane departure alert function
This function operates when all of the following conditions are met.
• LTA is turned on.
• Vehicle speed is approximately 32 mph (50 km/h) or more.
*1
• System recognizes white (yellow) lane lines or a course*2. (When a white
[yellow] line or course
*2 is recognized on only one side, the system will
operate only for the recognized side.)
• Width of traffic lane is approximately 9.8 ft. (3 m) or more.
• Turn signal lever is not operated.
• Vehicle is not being driven around a sharp curve.
• No system malfunctions are detected. (P. 409)
*1: The function operates even if the vehicle speed is less than approxi-
mately 32 mph (50 km/h) when the lane centering function is operating.
*2: Boundary between asphalt and the side of the road, such as grass, soil,
or a curb
●Steering assist function
This function operates when all of the following conditions are met in addi-
tion to the operation conditions for the lane departure alert function.
• Setting for (“LTA Steering Assist Mode”) in of the multi-
information display is set to “On”. (P. 220)
• Vehicle is not accelerated or decelerated by a fixed amount or more.
• Steering wheel is not operated with a steering force level suitable for
changing lanes.
• ABS, VSC, TRAC and PCS are not operating.
• TRAC or VSC is not turned off.
• Hands off steering wheel warning is not displayed. (P. 408)
4

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PRIUS PRIME_OM_OM47D71U_(U)
5-5. Using the driving support systems
●Vehicle sway warning function
This function operates when all of the following conditions are met.
• Setting for (“Lane Sway Warning Status”) in of the multi-
information display is set to “On”. (P. 220)
• Vehicle speed is approximately 32 mph (50 km/h) or more.
• Width of traffic lane is approximately 9.8 ft. (3 m) or more.
• No system malfunctions are detected. (P. 409)
●Lane centering function
This function operates when all of the following conditions are met.
• LTA is turned on.
• Setting for (“LTA Steering Assist Mode”) and (“Center
Trace”) in of the multi-information display are set to “On”. (P. 220)
• This function recognizes white (yellow) lane lines or the position of a pre-
ceding vehicle (except when the preceding vehicle is small, such as a
motorcycle).
• The dynamic radar cruise control with full-speed range is operating in
vehicle-to-vehicle distance control mode.
• Width of traffic lane is approximately 10 to 13 ft. (3 to 4 m).
• Turn signal lever is not operated.
• Vehicle is not being driven around a sharp curve.
• No system malfunctions are detected. (P. 409)
• Vehicle does not accelerate or decelerate by a fixed amount or more.
• Steering wheel is not operated with a steering force level suitable for
changing lanes.
• ABS, VSC, TRAC and PCS are not operating.
• TRAC or VSC is not turned off.
• Hands off steering wheel warning is not displayed. (P. 408)
• The vehicle is being driven in the center of a lane.
• Steering assist function is not operating.

PRIUS PRIME_OM_OM47D71U_(U)
4075-5. Using the driving support systems
5
Driving
■Temporary cancelation of functions
●When operation conditions are no longer met, a function may be temporarily
canceled. However, when the operation conditions are met again, operation
of the function is automatically restored. (P. 405)
●If the operation conditions (P. 406) are no longer met while the lane cen-
tering function is operating, the buzzer may sound to indicate that the func-
tion has been temporarily canceled.
■Steering assist function/lane centering function
●Depending on the vehicle speed, lane departure situation, road conditions,
etc., the driver may not feel the function is operating or the function may not
operate at all.
●The steering control of the function is overridden by the driver’s steering
wheel operation.
●Do not attempt to test the operation of the steering assist function.
■Lane departure alert function
●The warning buzzer may be difficult to hear due to external noise, audio
playback, etc.
●If the edge of the course
* is not clear or straight, the lane departure alert
function may not operate.
●Do not attempt to test the operation of the lane departure alert function.
*: Boundary between asphalt and the side of the road, such as grass, soil, or
a curb

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PRIUS PRIME_OM_OM47D71U_(U)
5-5. Using the driving support systems
■Hands off steering wheel warning
●When the system determines that the driver is driving without holding the
steering wheel while the system is operating
If the driver continues to keep their hands off of the steering wheel, the
buzzer sounds, the driver is warned and the function is temporarily can-
celed. This warning also operates in the same way when the driver continu-
ously operates the steering wheel only a small amount.
●When the system determines that the vehicle may deviate from the lane
while driving around a curve while the lane centering function is operating
Depending on the vehicle condition and road conditions, the warning may
not operate. Also, if the system determines that the vehicle is driving
around a curve, warnings will occur earlier than during straight-lane driving.
●When the system determines that the driver is driving without holding the
steering wheel while the steering wheel assist of the steering assist function
is operating.
If the driver continues to keep their hands off of the steering wheel and the
steering wheel assist is operating, the buzzer sounds and the driver is
warned. Each time the buzzer sounds, the continuing time of the buzzer
becomes longer.
■Vehicle sway warning function In the following situations, a warning mes-
sage urging the driver to hold the steering
wheel and the symbol shown in the illus-
tration are displayed on the multi-informa-
tion display to warn the driver. The
warning stops when the system deter-
mines that the driver holds the steering
wheel. Always keep your hands on the
steering wheel when using this system,
regardless of warnings.
When the system determines that the
vehicle is swaying while the vehicle sway
warning function is operating, a buzzer
sounds and a warning message urging
the driver to rest and the symbol shown in
the illustration are simultaneously dis-
played on the multi-information display.
Depending on the vehicle and road condi-
tions, the warning may not operate.

PRIUS PRIME_OM_OM47D71U_(U)
4095-5. Using the driving support systems
5
Driving
■Warning message
If the following warning message is displayed on the multi-information display
and the LTA indicator illuminates in orange, follow the appropriate trouble-
shooting procedure. Also, if a different warning message is displayed, follow
the instructions displayed on the screen.
●“LTA Malfunction Visit Your Dealer”
The system may not be operating properly. Have the vehicle inspected by
your Toyota dealer.
●“LTA Unavailable”
The system is temporarily canceled due to a malfunction in a sensor other
than the front camera. Turn the LTA system off, wait for a little while, and
then turn the LTA system back on.
●“LTA Unavailable at Current Speed”
The function cannot be used as the vehicle speed exceeds the LTA opera-
tion range. Drive slower.
■Customization
Function settings can be changed.
(Customizable features:P. 246)

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PRIUS PRIME_OM_OM47D71U_(U)
5-5. Using the driving support systems
RSA (Road Sign Assist)
The RSA system recognizes spe-
cific road signs using the front
camera to provide information to
the driver via the display.
If the system judges that the vehicle is being driven over the speed
limit, performing prohibited actions, etc. according to the recognized
road signs, it notifies the driver through a visual notification and notifi-
cation buzzer.
: If equipped
Summary of function
WARNING
■Before using the RSA
Do not rely solely upon the RSA system. RSA is a system which supports
the driver by providing information, but it is not a replacement for a driver’s
own vision and awareness. Drive safely by always paying careful attention
to the traffic rules.